The percentages of 13-year-olds performing at or above level 300 in 2012 were higher than in 1978 within each parental education category except for students whose parents had graduated from high school.

Mathematics scores for 13-year-olds were higher in 2012 than in 1978 at all five selected percentiles within all parental education categories except for students whose parents had graduated from high school.

Nine-year-olds are typically in 4th grade, 13-year-olds are typically in 8th grade, and 17-year-olds are typically in 11th grade. Some students in each age group, however, are in a grade that is below or above the grade that is typical for their age.